Which runs hotter, MH or HPS

[OlderStoner]

I have two nice lights in my grow, both 600w. One has an HPS the other has MH. The HPS was used in my last grow, the MH is a brand new bulb. This MH bulb gives off enormous heat. The grow room temp went from 78 to 83 within a day. I have another MH bulb which I used only a few times before but I don't remember them running so hot. I'm probably going to have to rethink this light setup. There will be less than 8 plants in a 5x5 tent. So I think the amount of lumens is correct, but this heat thing will have to be dealt with.

 

[OlderStoner]

Okay, after hearing only crickets on this one...I didn't find anything in my searches except that both types of lamps produce lots of heat. Next question. I have two 600 watt hoods in my grow tent. They are cooled by a single fan which produces enough CFM to do the job. Trouble is one of the hoods doesn't seal well at one end and some of the hot air leaks into the grow area. I've got other fans working on the area so while it's hot, it's not unbearable and the plants are doing nicely.

Now, I'd like to hear from others on this point. The lamps give off tremendous lumens and I have a cheap light meter which seems to work pretty good. When I place the light meter in the house it barely registers. When I take it outside in the sunshine as expected, the meter pegs all the way to the right and it's "off the scale" as we say. So I take the meter into the grow tent and when I place it directly beneath on of the lights the is goes off scale to the right again. I have tested this "off the scale" area inside the tent and found that in that zone I can lower the meter to about 18" below the lamps and the needle starts to move back to the left a little. When I get down to the plant canopy, which right now is about 36" below the lamps, the needle falls off slightly to the left. But at this distance the temp is comfortable for my hand, albeit warm. If I move my hand back up to the zone where the needle pegs, it's not that comfortable for my hand to be there. So I don't think it will be possible to move them into this max lumen zone without damaging or killing the plants.

The hoods are at the highest place I can set them inside of this tent. The plants will of course be closing the distance between themselves and these lamps over the next week of veg, then I'm moving them into 12/12 for flowering.

 

[Dano2k3]

If you and get some CO2 you can run a little hotter and be just fine...